Self-developing film must be passed after exposure between a pair of transport and squeeze rollers that clench it tightly as it moves through between them. This action ruptures a capsule of developing chemicals at the leading end of the piece of film, forcing these chemicals downstream along the piece to its trailing end to initiate the self-developing process.
These rollers are cylindrical and each have at each end a coaxial small-diameter trunnion. Each trunnion fits snugly in the cylindrical hole of a respective journal that holds it snugly while permitting it to rotate freely. The journal holes of each roller are coaxial with each other and with the respective roller, and the journal two axes are parallel. The structure forming the journal holes of one of the rollers is limitedly displaceable in a direction away from the other roller, that is in the plane of the two journal axes, but is biased in this direction toward the other roller so that the rollers are biased together with the appropriate and considerable pressure, which is exerted on the film passing between these two rollers.
These rollers are subject to considerable wear. In addition they can become fouled with chemicals if something goes wrong, and it is possible for the film to jam up in the apparatus at these rollers. Thus it is necessary to take out and reinstall the rollers occasionally. This is a relatively onerous job that is normally left to a professional camera repairer, or is undertaken only by a fairly handy person. As described in German Pat. No. 2,732,973 the journals are held in place by screws which must be removed to free the rollers enough to get them out. Furthermore it is necessary to take out both rollers, even if only one needs removal.